Boiler and control system therefor



Sept. 20, 1955 H. A. GRAY BOILER AND CONTROL SYSTEM THEREFOR Filed July 24, 1952 Pressu re I 46 yW/ United States BQEER CONTROL SYSTEM THEREFOR Howard A. Gray, Godfrey, 111. Application July 24, 1952, Serial No. 300,729 6 Claims. (Cl. 12244 8) This invention relates to mechanically fired steam bo le s In fiI'QrbOX boilers now in common use in which the crown plate is used as a water-heating surface, every effort is made to keep the crown plate submerged. If the water level in such a boiler gets down below the crown plate while there is a fire under it, and cold water is injected into the boiler onto the over-heated crown plate, the boiler is likely to explode, or at least crack. At the same, time, the crown sheet of a firebox is recognized as the most elfective heating surface in the boiler.

One of the objects of this invention is to provide a safe quick-acting boiler in which the efficiency of the crownplate as a steam generating source is utilized.

Other objects will become apparent from the following description in which will be set forth an illustrative embodiment of this invention. It is understood, however, that this invention is susceptible of various embodiments, within the scope of the appended claims, without departing from the principles or spirit of the invention.

In accordance with this invention, generally stated, a vaporizer is provided which is exposed on its outside surface directly to the products of combustion of a firebox, as well as to radiant heat from that source. Water is sprayed onto the hot surfaces of the vaporizer. The flow of water is begun before the vaporizer is heated, and is continued until the heat applied thereto is reduced to a safe level.

The water which is not converted to steam is removed from the vaporizer and re-circulated. Where the installation admits of returning the condensate, that condensate may be re-circulated as is customary in steam plant practice. The feed water may be pre-heated by flue a In the d a n Figure 1 is a side view, partly in section, of a boiler installation constructed in accordance with one embodimea o t in n n;

Figure 2 is a fragmentary side view, partly in section, of another embodiment of this invention;

Figure 3 is a somewhat diagrammatic view of a boiler installation constructed in accordance with this invention, showing an electric control system therefor;

Figure 4 is a somewhat diagrammatic fragmentary view of an auxiliary flooding system for a boiler or this invention;

Figure 5 is a detail plan view of the valve system of the device shown in Figure 4;

Figure 6 is a view in side elevation of the valve system shown in Figure 5; and,

Figure 7 is a diagrammatic view of an alternative electric control system.

Referring now to the drawings for an illustrative embodiment of this invention, 1 represents a steam boiler installation. The installation 1 consists of a firebox 2 in which is an oil burner 3. operated by a burner motor 4. Directly above the firebox 2 is a vaporizer 10 of this invention. In the embodiment shown in Figure 1, the

2,718,218 Patented Sept. 20, 1955 Free vaporizer is a pressure-tight cylindrical shell, situated within a flue 12. The walls of the flue 12 are hollow and form a water jacket 14 through which feed water is circulated for pre-heating. The fiue 12 is connected to a stack 11. The vaporizer 10 is provided with a feed water inlet 15, a vaporizer drain 16, and a steam takeoff conduit 20.

In the embodiment of vaporizer shown in Fig re 1, the feed water inlet 15 discharges, onto an umbrella-. shaped distributing plate 25 which distributes the feed water in a sheet on the inside vertical surfaces of the vaporizer shell. The steam takeoff conduit of this embodiment takes the form of an L-shaped pipe 21 extending up under the distributing plate 25 so as to be. protected from the feed water. The feed water inlet pipe 15 is connected to the water jacket 14. The drain 16 from the bottom of the vaporizer is connected, through a steam trap 28, to the suction side of a feed water pump 26, the pressure side of which pump is con. nected to the water jacket 14 by a feed water pipe 27.

In the embodiment of this invention shown in Figure 2, the steam takeoff conduit 20 leads directly from the uppermost part of the vaporizer. The feed water inlet 15 extends to the center axis of the vaporizer and is provided with a ball spray 22, by which the feed water is thrown against the inside surfaces of the vaporizer. As in the embodiment shown in Figure 1, a drain 16 is connected to the suction side of a feed water pump 26, while the feed water inlet 15 is connected to the water jacket 14.

In all of the embodiments shown, a control system is provided which is shown diagrammatically in Figure 3. In the system shown in that figure, the primary control of the circuit is accomplished by a thermostatic switch 30. One terminal 31 of the thermostatic switch 3% is shown as connected to one wire 32 of a two-wire power line 33. The other terminal 34 of the thermostatic switch is connected through a steam pressure switch 35 and a first water pressure switch to a pump motor 45, which pump motor operates the feed pump 26. The pump motor is connected by a wire 46 to the remaining wire 36 of the power line 33. The thermostatic switch 30 is connected through the steam pressure switch 35, first water pressure switch 40 and a second water pressure switch 50 to the burner motor 4. The burner motor 4 is connected directly to the wire 36 of the power line 3.3 by a wire The steam pressure switch 35 is connected to the steam takeoff conduit 26. It is normally closed, opening in response to excessive steam pressure in the system. The first water pressure switch 40 is connected to the feed waterpipe 27. It is also normally closed, opening in response to abnormally high water pressure in the feed water pipe 27. The second water pressure switch 50 is also connected to the feed water pipe 27. It is normally open, closing in response to normal operating water pressure in. the feed water pipe 27.

In operation, assume that the thermostatic switch 30 is open. The pump motor 45 and the burner motor 4 are not running since their circuits, through the thermostatic switch 30, are broken. Steam pressure switch 35 and first water pressure switch 40 are closed; second water pressure switch 50. is open. Ifnow the thermostatic switch- 30 is closed (as in response to a drop in temperature), pump motor 45 will be energized to. run the pump 26 to begin to pump feed water through feed water pipe 27, the water jacket 14, and through the feed water inlet 15, into the vaporizer it). When the pressure of water in the feed water pipe 27 has reached the level at which the second water pressure switch 59 closes, the burner motor 4 will be energized and the oil burner 3 will operate to heat the vaporizer 10.. It can be seen that sincethe flow of water to the vaporizer has already begun before the burner is turned on, there is no danger of overheating the vaporizer.

When the thermostatic switch again opens, both the pump motor and the burner motor are de-energized. Any water remaining in the vaporizer will tend to take care of the latent heat of the firebox, which in most installations is low.

The steam pressure switch may function either as a regulating device, to hold the pressure between given limits (a sharp lower limit being achieved by the almost instantaneous generation of steam in the vaporizer when the system is put into operation), or simply as a safety device. In either event, when the steam pressure exceeds an amount for which the switch 35 is set, it acts to deenergize both the pump and burner motors. If, through failure of the pump motor 45, or a lack of water, the pressure on the second water pressure switch drops below a safe limit, that switch will cut out the burner motor and keep it out until the water pressure again builds up. On the other hand, if, because of clogging of the water inlet pipe nozzle, or the like, the pressure in the feed water intake pipe 27 builds up excessively, the first water pressure switch 40 will cut out both the pump motor and the burner motor until the water pressure is reduced.

In using the vaporizer with a chain grate coal stoker or other installation in which the de-energizing of the fuel feed control motor does not result in a substantially instantaneous extinguishing of the flame, or in which the residual heat is high, a system such as that shown in Figures 46 may be used. As shown in Figure 4, an auxiliary water supply tank is provided which is connected to the drain 16 of the vaporizer 10 by means of a pipe 72. In the pipe 72 is a valve 73. In the drain 16, beyond its connection with the auxiliary water supply tank pipe 72 is another valve 75. The valves 73 and 75 are connected by a lever arm pivoted at 81 between them. At one end of the lever arm 80 is a weight 82. Pivotally c011- nected to the other end of the lever arm is a solenoid 85. In the embodiment shown, the valve 73 is biased into closed position by the solenoid $5, while the valve 75 is biased into open position thereby while the pump and stoker feed motors are energized. However, when the thermostatic switch 30 opens to break the pump and stoker motor circuits, the solenoid 85 is de-energized and the weight 82 acts to open the valve 73 and close the valve 75, allowing water from the auxiliary water supply tank 70 partially to flood the vaporizer. In this way, the heat from the fuel bed, or the residual heat in the furnace, cannot damage the vaporizer.

An illustrative example of another method of insuring against overheating of the vaporizer after the fuel feeding circuit is broken is shown in Figure 7. In that figure, a by-pass 89 around a main thermostatic switch 130 is provided in the feed water pump circuit. A thermally responsive switch 90 in the by-pass 89 is arranged to be operated by the temperature of the feed water. The thermally responsive switch 90 is connected at one side with the power line wire 32, and on the other side between the thermostatic switch and the steam pressure responsive switch 35. In this arrangement, however, the main thermostatic switch 130 is provided with a third contact 92 which is connected to operate a relay switch 93, between the first water pressure switch 40 and the second water pressure switch 50. When the thermostatic switch 130 is closed, all three contacts meet. When the thermostatic switch 130 is open, all three contacts are separated. In the operation of this device, assume that the thermostatic switch 130 and the thermally responsive switch 90 are open. The relay switch 93 is also open. When the thermstatic switch 130 closes, the relay switch 93 also closes, and the system operates just as it does in the embodiment shown in Figure 3. As the feed water recirculates and becomes hot, the thermally responsive switch 90 closes. This has no effect on the circuit as long as the thermostatic switch 130 remains closed. When thermostatic switch 130 opens again, however, relay switch 93 also opens to break the circuit to the burner motor 4, but, as long as the temperature of the feed water remains sufficiently high to keep the thermally responsive switch 90 closed, the feed water pump will continue to operate. Since the temperature of the feed water, as far as operating the thermally responsive switch is concerned, is dependent solely upon the amount of heat supplied by the furnace, it can be seen that the thermally responsive switch 90 effectively senses the amount of heat in the furnace.

The boiler of this invention is cheap, simple, safe, and quick acting. The spraying of the feed water on the hot ides of the vaporizer brings the water into intimate contact with the heated surface, provides for efiicient utilization of the heat and therefore for high efficiency of the boiler. Since the flow of feed water is begun before firing of the boiler furnace is begun, and continues until the firing is stopped, there can be no danger of explosion.

The boiler of this invention is also compact, since only enough water need be used to maintain an adequate circulation, and the bulk of the volume of the vaporizer can thus serve as steam space.

Those interior surfaces of the vaporizer which feed water does not contact may act act as superheating surfaces.

Numerous variations in the construction of the various elements of this invention within the scope of the appended claims will become apparent to those skilled in the art in the light of the foregoing disclosure. For example, a flow meter may be used in place of the water pressure switch 50. Such an arrangement is, in many respects, preferable, since it is the flow of water rather than the water pressure which is of importance so far as the operation of the burner is concerned. The vaporizer shell may be turned on its side, so long as adequate drainage and a proper feed water distribution is ensured, to exhibit more surface to the radiant heat of the fire than is exposed in the vertical setting. The shape of the vaporizer may also be varied.

Auxiliary flooding devices other than the one illustrated may be used to flood the vaporizer in the event of feed water pump failure, feed water supply failure or any other exigency by which the flow of feed water is not maintained, as well as under the circumstances described in connection with the auxiliary water supply system of Figures 4-6. The primary control need not be a thermostatic switch, but may be a hand switch or a steam-pressure responsive switch or the like. The boiler of the invention is not confined to the use of water. The term water is used herein to exemplify any suitable liquid.

Having thus described my invention what is claimed and desired to be secured by Letters Patent is:

l. A steam boiler installation and control comprising a furnace having automatic firing means, a vaporizer positioned to be heated in said furnace, distributing means within said vaporizer to distribute a sheet of water on inside surfaces of said vaporizer, a feed water pump connected to supply water under pressure to said distributing means and to drain said vaporizer, a switch responsive to flow of water from said feed water pump to said distributing means connected to energize said automatic firing means when the flow of feed water is at a normal velocity, and to de-energize said automatic firing means when the said flow is at a lower velocity, and a second switch responsive to water pressure from said feed water pump connected to permit energization of both the said firing means and the said feed water pump when the water pressure from said feed water pump is below a preset abnormally high level and to tie-energize both said firing means and said feed water pump when the water pressure from said feed water pump reaches the said abnormally high level.

2. In combination with a steam boiler installation wherein a vaporizer, along inside surfaces of which water is circulated in a thin sheet by means of a p'ump is arranged to be heated by a furnace fired by automatic firing means, a control system comprising means for initiating the operation of the said pump, means, responsive solely to the successful operation of said pump, initiating the operation of said automatic furnace firing means, and means responsive to an abnormally high water pressure between said pump and said vaporizer to stop the operation both of the said pump and the said automatic furnace firing means.

3. In combination with a steam boiler installation wherein a vaporizer, along inside surfaces of which water is circulated in a thin sheet by a pump, is arranged to be heated by a furnace fired by automatic firing means, said vaporizer being substantially drained of water by the operation of said pump, the suction side of which is connected to said vaporizer by a drain; a vaporizer flooding device comprising an auxiliary water supply connected to said vaporizer by means of a pipe, a valve in said pipe, a valve in said drain, and control means responsive to the de-energization of said pump to open said auxiliary water supply valve and to close said drain valve.

4. A steam generating system and control therefor comprising a furnace having automatic firing means controlled by an electric circuit, a vaporizer positioned to be heated in said furnace, a feed water inlet to said vaporizer, means for delivering water to said feed water inlet, a first switch, normally biased to closed position but responsive to excessive pressure of water in the feed water inlet to move to open position to break the electric circuit controlling the firing means and to stop the delivery of water to the feed Water inlet, and a second switch in the electric circuit controlling the firing means, said second switch being normally biased to open position but being responsive to a preset minimum pressure of water delivered to the feed water inlet to move to closed position to complete the said electric circuit and thereby to energize said firing means, said first and second switches defining an upper and lower operating range of feed water pressures.

5. A steam generating system and control therefor comprising a furnace having an automatic firing means controlled by an electric circuit, a vaporizer positioned to be heated in said furnace, a feed water inlet to said vaporizer, a steam line from said vaporizer, means for delivering water to said feed water inlet, a first switch, normally biased to closed position but responsive to excessive pressure of water in the feed water inlet to move to open position to break the electric circuit controlling the firing means and to stop the delivery of water to the feed water inlet, a second switch, in the said electric circuit, being normally biased to open position but being responsive to the delivery of water to the feed water inlet to move to closed position to complete the said electric circuit and energize said firing means, and a third switch, normally biased to closed position but being responsive to excessive pressure of steam in the steam line to move to open position to break the electric circuit controlling the firing means and to stop the delivery of water to the feed water inlet.

6. In combination with a steam generating system wherein a vaporizer, along inside surfaces of which water is circulated and recirculated in a thin sheet, is arranged to be heated by a furnace fired by automatic firing means, a control system comprising means for delivering water to said vaporizer, means, responsive solely to the delivery of said water, initiating the operation of said firing means, and means responsive to the temperature of the recirculated water to maintain the delivery of said water to said vaporizer so long as the temperature of said water exceeds a set predetermined limit independently of the operation of said automatic firing means.

References Cited in the file of this patent UNITED STATES PATENTS 1,827,950 Mulligan Oct. 20, 1931 1,942,436 MacDonald Jan. 9, 1934 1,951,350 Doble Mar. 20, 1934 1,975,104 Junkins Oct. 2, 1934 2,335,655 Dickey Nov. 30, 1943 2,428,905 Bilan Oct. 14, 1947 2,548,081 Touloukian Apr. 10, 1951 

